The mammalian cdc2 protein kinase: mechanisms of regulation during the cell cycle
|
|
- Harry Harper
- 5 years ago
- Views:
Transcription
1 J. Cell Sci. Suppl. 12, (1989) Printed in Great Britain The Company of Biologists Limited The mammalian cdc2 protein kinase: mechanisms of regulation during the cell cycle GIU LIO DRAETTA a n d DAVID BEACH Cold Spring Harbor Laboratory, P.O. Box 100, Cold Spring Harbor, New York 11724, USA Summary Recent experimental evidence has demonstrated the central role of the cdc2 protein kinase in the transition from G 2 to M phase in eukaryotic cells. We shall review our knowledge of the mechanisms which coordinate activation of the kinase with cell cycle-specific events in mammalian cells. The origins: cdc2+ and the fission yeast cell cycle In the fission yeast Schizosaccharomyces pombe the cell cycle is regulated at two steps, one acting in G i before D N A synthesis, the other in G 2 (Fantes and Nurse, 1977; Nasmyth, 1979). In the mid 1970s a number of cell cycle control genes were identified. Among them cdc2+ was particularly interesting because its function is required in G j, as well as in G 2 for the initiation of mitosis (Nurse and Bissett, 1981). In addition to lethal temperature-sensitive mutations in the cdc2+ gene, dominant wee mutations were described, which cause cells to undergo mitosis prematurely (Nurse, 1975). Therefore, cdc2+ acts at a rate-limiting step, which integrates cellular informations (cell size, completion of D N A synthesis etc.) and determines the timing of mitosis. cdc2+ is homologous to a previously described Saccharomyces cerevisiae cell cycle gene, CDC28. The two genes are functionally interchangeable: CDC28 can rescue S. pombe cdc2 mutations and a cdc2+ intronless gene can rescue cdc28 mutations of S. cerevisiae (Beach et al. 1982; Booher and Beach, 1986). The two genes both encode 34K (K = 103ilfr) polypeptides, which are 62% identical at the amino acid level and contain regions that are highly conserved among the family of Ser/Thr kinases. In addition both proteins have kinase activity in vitro (Reed et al. 1985; Simanis and Nurse, 1986; Brizuela et al. 1987). Given the universality of the basic organization of the cell cycle in all eukaryotes (ordered phases of D N A synthesis and nuclear division) it was legitimate to guess that cell cycle control elements might be conserved throughout evolution. A homologous cell cycle control kinase is, after all, present in two evolutionary very distance species (S. pombe and 5. cerevisiae). Based on this reasoning, an investigation into cell cycle control genes in higher eukaryotes was initiated. Key words: cdc2, tyrosine phosphorylation, protein kinase.
2 G. Draetta and D. Beach 22 The com ponents of the cdc2 com plex and their regulation (1) p34cdc2 Using monoclonal antibodies against fission yeast cdc2 which cross-reacted with the S. cerevisiae CDC28 protein, we identified a 34K protein kinase in human HeLa cells (Draetta et al. 1987). Proteolytic mapping, kinase activity of the immunoprecipitates and association of the human protein with the homolog of the s u c l + gene product of yeast (see below), unequivocally confirmed that a human cdc2 homolog had been found. A human cd N A sequence that was able to complement a temperature-sensitive mutation of cdc2+ in fission yeast was also cloned and sequenced (Lee and Nurse, 1987). This sequence showed 62% similarity to the fission yeast cdc2 sequence. Insight into the possible role of human cdc2 in cell cycle regulation was gained through investigation of the properties of cdc2 at different stages of the cell cycle (Draetta and Beach, 1988). As in fission yeast, the levels of the protein in the cell are constant during the cell cycle. However, phosphorylation of cdc2 appears to be cell cycle-regulated (Fig. 1). In G j cdc2 is dephosphorylated and phosphate accumulates on the protein as cells progress through S and G 2. Monomeric unphosphorylated cdc2 is inactive, as a protein kinase, whereas phosphorylated cdc2 is able to phosphorylate the artificial substrate casein in vitro (Draetta and Beach, 1988; Brizuela et al. 1989). Anaphase - Anaphase M etaphase -> Interphose M etaphase In te rp h a se Fig. 1. Model of the activation of the cdc2 kinase complex. In G i, cdc2 is unphosphoryl ated. During S and G 2, progressive accumulation of cyclin and phosphorylation of the cdc2 subunit leads to complex formation. At mitosis, cdc2 becomes dephosphorylated and it is maximally active. According to this model, phosphorylation of the cyclin subunit is the signal for its degradation and exit from mitosis.
3 Cell cycle of mammalian cells 23 The most highly phosphorylated form of cdc2 is associated with a 62K protein (p62, probably corresponding to human cyclin B; see below, and Fig. 1). Dephosphorylation of cdc2 protein when it is complexed with p62 probably triggers maximal activation of the kinase against endogenous p62 and added histone-hj or casein. Interestingly, cdc2 is phosphorylated in vivo not only on threonine and serine but also on tyrosine residues. Using anti-phosphotyrosine antibodies we found that, phosphotyrosine progressively accumulates on cdc2 as cells move from G i to S and G 2 (Draetta et al. 1988), and is lost at mitosis. Recently cdc2 was found to be a component of the M phase-specific histone-hj kinase of starfish oocytes (Arion et al. 1988; Labbé et al. 1988). This enzyme is a cyclic AM P and calmodulin-independent protein kinase, with a high affinity for histone-hi. Its cyclic activation at mitosis had suggested a possible involvement in cell cycle regulation. Also, the possibility of mediating chromosome condensation through phosphorylation of histone-hj had been suggested. Purified preparations of starfish histone-hi kinase contain equimolar amounts of cdc2 and a B-type cyclin, as described by Dorée et al (this volume). A cdc2 homolog is a component of the maturation-promoting factor (MPF) of Xenopus eggs (Dunphy et al. 1988; Gautier et al. 1988). MPF is a cellular factor that is able to induce meiotic maturation when injected in Xenopus oocytes that are arrested at the G 2/prophase boundary of the first meiotic division (Masui and Markert, 1971; Smith and Ecker, 1971). MPF activity has been detected in oocytes from a number of different vertebrate and invertebrate species. In addition, MPF can be detected in mitotic cells from sea urchin and amphibian embryos, as well as in yeast and mammalian cells (Kishimoto, 1988). (2) p!3 s cl su c l+ was isolated as a D N A sequence that rescues some but not all temperaturesensitive alleles of cdc2 when expressed on a multicopy plasmid. Disruption of the su c l+ gene causes cell cycle arrest, confirming a direct involvement of this gene in cell cycle control (Hayles et al. 1986; Hindley et al. 1987). The D N A sequence of the su c l+ gene encodes a protein of 113 amino acids (Hindley et al. 1987), which has been identified in yeast. Its abundance does not alter during the cell cycle or during entry into stationary phase (Brizuela et al. 1987). p 13 is complexed with the cdc2 gene product and the pl3sucl-p34cdc2 complexes have kinase activity. In addition, the stability of cdc2/sucl complexes is altered in strains carrying temperaturesensitive alleles of cdc2 which are suppressible by overexpression of the su c l+ gene (Brizuela et al. 1987). Kinase activity can be restored in vitro by addition of purified p 13 to the assay (Booher et al. 1989). In human cells, we have detected a homolog of the su c l+ protein. (Draetta et al. 1987). As in fission yeast, this protein is complexed with the cdc2 protein. In addition, recombinant yeast pl3sucl expressed in Escherichia coli is able to bind the cdc2 kinase in vitro and such complexes possess very high kinase activity. pl3sucl is able to bind both the p34cdc2 monomer and the cdc2 high molecular weight complex (Brizuela et al. 1989). P13 is neither a substrate nor an inhibitor of the cdc2 kinase.
4 24 G. D raetta and D. Beach At present we do not have any direct evidence for the role of the pl3 protein in the regulation of the cdc2 kinase complex. (3) p62 (cyclin B) p62 was identified as a component of the human cdc2 complex (Draetta and Beach, 1988). Immunoprecipitates from 35S-labeled or 32P-labeled HeLa cells with anticdc2 antibodies show a 62K band in addition to the p34 and p 13 bands. We have demonstrated a specific interaction between p34 and 62K species (Draetta and Beach, 1988; Brizuela et al. 1989). As already mentioned, p34 must be phosphorylated in order to interact with p62. p62 is a substrate of the cdc2 kinase in vitro. Using the phosphorylation of p62 in immunoprecipitates we have recently purified the human mitotic cdc2 complex (Brizuela et al. 1989). The sudden loss of activity of the cdc2 kinase at the end of mitosis and the concomitant loss of p62 from the complex suggested the possibility that the 62K protein might be a mitotic cyclin. The cyclins are proteins originally identified in clam and sea urchin eggs, which are synthesized after fertilization, accumulate across each cell cycle and are abruptly degraded at the end of each mitosis (Rosenthal et al. 1980, 1983; Evans et al. 1983). Injection of cyclin A or B m RN A into unfertilized Xenopus oocytes leads to resumption of the meiotic divisions and appearance of M PF activity (Swenson et al. 1986; Pines and Hunt, 1987; Westendorf et al. 1989). In a recent paper (Draetta et al. 1989) we have demonstrated a direct biochemical interaction between cdc2 and the clam cyclin A and B. In the clam Spisula solidissima we have identified a 34K cdc2 homolog. Together with cdc2, cyclin A and B are bound to pl3-sepharose. The pl3-bound complex as well as anti-cyclin A or B immunoprecipitates show histone-hi kinase activity. The kinase activity is only present in precipitates prepared from M phase but not interphase egg extracts. A human cyclin B clone has recently been identified (Pines and Hunter, 1989). Antibodies against a bacterially expressed cyclin B recognize the HeLa p62 (Draetta et al. unpublished). p62 is therefore the human homolog of cyclin B. The S. pombe cd cl3 + gene encodes a cyclin B homolog (Solomon et al. 1988; Goebl and Byers, 1988). Its gene product forms a stable complex with the fission yeast cdc2, and is an endogenous substrate of the kinase complex (Booher and Beach, 1988; Booher et al. 1989). As in human cells this complex shows cell cycle-regulated histone-hi kinase activity. InXenopus extracts, ablation of cyclin m RN A also blocks M PF activity (Minshull et al. 1989). In addition, it has been recently demonstrated that cyclin B m RN A is the only message needed to be translated in order to induce interphase Xenopus extracts to undergo M phase (Murray and Kirschner, 1989; Murray et al. 1989). cdc2 regulation: solved and unsolved matters During the first two years following the identification of a mammalian cdc2 homolog we developed a number of reagents that have advanced our knowledge of the regulation of the cdc2 kinase in mammalian cells. The observations in human cells
5 Cell cycle of mammalian cells 25 have strongly reinforced the idea of a direct involvement of cdc2 in mitotic control. Polyclonal and monoclonal antibodies produced against the yeast cdc2 protein, an anti-peptide serum which is able to recognize multiple phosphorylated forms of the cdc2 protein, and the recombinant pl3 protein have been utilized to produce our second generation cdc2 reagents. Purified preparations of the cdc2 monomer as well as of the complex are now available (Draetta et al. 1988; Brizuela et al. 1987) and they will allow us to address the following new and interesting questions. (1) What is the structure of the cdc2 complex at mitosis (and, just as important, what is the structure of the mammalian MPF)? Are there different mitotic-specific cdc2 kinases? (2) What are the kinases that phosphorylate cdc2? Is cdc2 a substrate of the weel kinase (the existence of w e e l+ homologs in species other than fission yeast is strongly suggested by the experiments of Russell et al. 1989). What are the tyrosine kinases that phosphorylate cdc2? Is their activity cell cycle-regulated? What is the nature of the phosphatases involved? What is the sequence of the phosphorylation events? (3) What is the role of the fission yeast cdc25+ homolog in the activation of mitosis (Russell et al. 1989); does it show a specific interaction with the cdc2 complex? (4) Is cdc2 phosphorylation or cyclin formation the rate-limiting step in the complex assembly in vivo? (5) What is the role of the pl3 protein? It is not a substrate nor an inhibitor/activator in vitro. Could it be a docking factor, which drives the cdc2 complex to some cellular components? (6) What are the cdc2 substrates? The study of the phosphorylation of the endogenous p62 cyclin B subunit will provide us with a starting point for the characterization of other cdc2 substrates, at least in terms of their biochemical requirements. Histone-Hi, which has a very low K m for cdc2, might be a physiological substrate. In fact, sites phosphorylated in vivo at mitosis are also phosphorylated in vitro. It is clear that given the large number of proteins that are phosphorylated at mitosis two types of hypothesis can be formulated, one in which cdc2 acts as the master kinase, catalyzing the phosphorylation of all substrates directly. The other cascade model would predict a number of more specific protein kinases, which are themselves substrates for cdc2 and catalyze - phosphorylation of specific subcellular components. In conclusion, we would like in the not too distant future to be able to use purified cellular components and reproduce in vitro the events that lead to mitosis in eukaryotes. Together with yeast genetics and molecular biology, and the study of the biology of MPF in early embryos, the newly born mammalian cdc2 biochemistry will probably add new elements to this goal. References A r io n, D., M eijer, L., Brizu ela, L. and Beach, D. (1988). cdc2 is a component of the M phase specific histone-histone-h! kinase: evidence for identity with M PF. Cell 55, Beach, D. H., D urkacz, B. and N urse, P. M. (1982). Functionally homologous cell cycle control genes in budding and fission yeast. Nature, Lond. 300, Booher, R. and Beach, D. (1986). Site-specific mutagenesis of cdc2+, a cell cycle control gene of the fission yeast Schizosaccharomyces pombe. Molec. cell. Biol. 6, Booher, R. and Beach, D. (1988). Involvement of cdcl3+ in mitotic control in Schizosaccharo-
6 26 G. D raetta and D. Beach myces pombe: possible interaction of the gene product with microtubules. EMBO J. 7, Booher, R., A lfa, C., H yams, J. an d Beach, D. (1989). The fission yeast cdc2/sucl/cdcl3 protein kinase: regulation of catalytic activity and cellular localization. Cell 58, Br izu ela, L., D raetta, G. and Beach, D. (1987). pl3sucl acts in the fission yeast cell division cycle as a component of the p34cdc2 protein kinase. EMBO J. 6, Br izu ela, L., D raetta, G. and Beach, D. (1989). Activation of cdc2 as a histone-h! kinase is associated with complex formation with the p62 subunit. Proc. natn. Acad. Sci. U.S.A. 86, D orée, M., L abbé, J.-C. & Pic a r d, A. (1989). M phase promoting factor: its identification as the protein kinase encoded by the cell cycle control gene CDC2 and its activation by dephosphorylation. jf. Cell Sci. Suppl. 12, D raetta, G., Br izu e l a, L., Potashkin, J. a n d Beach, D. (1987). Identification of p34 and pl3, human homologs of the cell cycle regulators of fission yeast encoded by cdc2+ and su c l+. Cell 50, D raetta, G. and Beach, D. (1988). Activation of cdc2 protein kinase during mitosis in human cells: cell cycle-dependent phosphorylation and subunit rearrangement. Cell 54, D raetta, G., Piw n ic a-worms, H., M orrison, D., D ruker, B., R oberts, T. and Beach, D. (1988). cdc2 is a major cell-cycle regulation tyrosine kinase substrate. Nature, Land. 336, D raetta, G., L uca, F., W estendorf, J., Br izu e l a, L. and Beach, D. (1989). cdc2 protein kinase is complexed with both cyclin A and B: evidence for proteolytic inactivation of MPF. Cell 56, D unphy, W. G., Br izu ela, L., Beach, D. and N ewport, J. (1988). The Xenopus homolog of cdc2 is a component of MPF, a cytoplasmic regulator of mitosis. Cell 54, Evans, T., R osenthal, E., Y oungbloom, J., D istel, D. and H unt, T. (1983). Cyclin: a protein specified by maternal m R N A in sea urchin eggs that is destroyed at each cell division. Cell 33, Fantes, P. and N urse, P. (1977). Control of cell size in fission yeast by a growth modulated size control over nuclear division. Expl Cell Res. 107, G autier, J., N orbury, C., L ohka, M., N urse, P. a n d M aller, J. (1988). Purified maturation- Promoting factor contains the product of a Xenopus homolog of the fission yeast cell cycle control gene cdc2+. Cell 54, G oebl, M. and Byers, B. (1988). Cyclin in fission yeast. Cell 54, H ayles, J., Beach, D., D u rkacz, B. an d N urse, P. (1986). The fission yeast cell cycle control gene cdc2+: isolation of a sequence sucl that suppresses cdc2 mutant function. Molec. gen. Genet. 202, H in d l e y, J., Ph ea r, G. A., Stein, M. and Be ach, D. (1987). su c l+ encodes a predicted 13 kilodalton protein that is essential for cell viability and directly involved in the division cycle of Schizosaccharomyces pombe. Molec. cell. Biol 7, K ishimoto, T. (1988). Regulation of metaphase by a maturation-promoting factor. Dev. Growth Differ. 30, K ishimoto, T., K uriyam a, R., K o n d o, H. a n d K anatani, H. (1982). Generality of the action of various maturation-promoting factors. Expl Cell Res. 137, L abbé, J., L ee, M., N urse, P., Pic a r d, A. and D orée, M. (1988). Activation at M-phase of a protein kinase encoded by a starfish homologue of the cell cycle control gene cdc2+. Nature, Lond. 335, L e e, M. a n d N urse, P. (1987). Complementation used to clone a human homologue of the fission yeast cell cycle control gene cdc2+. Nature, Lond. 327, M a su i, Y. and M arkert, C. (1971). Cytoplasmic control of nuclear behaviour during meiotic maturation of frog oocytes. J '. exp. Zool. 177, M in sh u ll, J., Bl o w, J. and H unt, T. (1989). Translation of cyclin mrna is necessary for extracts of activated Xenopus eggs to enter mitosis. Cell 56, M orla, A., D raetta, G., Beach, D. an d W a n g, J. (1989). Reversible tyrosine phosphorylation of cdc2: dephosphorylation accompanies activation during entry into mitosis. Cell 58, M u rray, A. and K irschner, M. (1989). Cyclin synthesis drives the early embryonic cell cycle. Nature, Lond. 339,
7 Cell cycle of mammalian cells 27 M urray, A. W., Solom on, M. J. and K irschner, M. W. (1989). The role of cyclin synthesis and degradation in the control of M PF activity. Nature, Land. 339, N asmyth, K. (1979). A control acting over the initiation of D N A replication in the yeast Schizosaccharomyces pombe. J. Cell Sci. 36, N urse, P. (1975). Genetic control of cell size at division in yeast. Nature, Lond. 256, N urse, P. and Bissett, Y. (1981). Gene required in Gi for commitment to cell cycle and in G 2 for control of mitosis in fission yeast. Nature, Lond. 292, Pin e s, J. and H unt, T. (1987). Molecular cloning and characterization of the mrna for cyclin from sea urchin eggs. EM BO J. 6, Pines, J. and H unter, T. (1989). Isolation of a human cyclin cdna: evidence for cyclin mrna and protein regulation in the cell cycle and for interaction with p34cdc2. Cell, in press. R e e d, S. I., H a d w ig e r, J. A. an d L o r in c z, A. T. (1985). Protein kinase activity associated with the product of the yeast cell cycle genes CDC28. Proc. natn. Acad. Sci. U.S.A. 82, R osenthal, E., H unt, T. and R u derm an, J. (1980). Selective translation of mrna controls the pattern of protein synthesis during early development of the surf clam, Spisula solidissima. Cell 20, R osenthal, E., T ansey, T. and R u derm an, J. (1983). Sequence-specific adenylations and deadenylations accompany changes in the translation of maternal mrna after fertilization of Spisula oocytes. J. molec. Biol. 166, R ussell, P., M oreno, S. a n d R eed, S. (1989). Conservation of mitotic controls in fission and budding yeasts. Cell 57, Sim a n is, V. and N urse, P. (1986). The cell cycle control gene dcd2+ of yeast encodes a protein kinase potentially regulated by phosphorylation. Cell 45, Smith, L. an d E cker, R. (1971). The interaction of steroids with Rana pipiens oocytes in the induction of maturation. Devi. Biol. 25, Solom on, M., Booher, R., K irschner, M. and Beach, D. (1988). Cyclin in fission yeast. Cell 54, Sw enson, K., Farrell, K. a n d R uderm an, J. (1986). The clam embryo protein cyclin A induces entry into M phase and resumption of meiosis 'mxenopus oocytes. Cell 47, W estendorf, J. M., Sw en so n, K. I. and R u derm an, J. V. (1989). The role of cyclin B in meiosis I.J. Cell Biol. 108,
8
Cyclin synthesis and degradation and the embryonic cell cycle
y. Cell Sci. Suppl. 12, 65-76 (1989) Printed in Great Britain (E ) The Company of Biologists Lim ited 1989 65 Cyclin synthesis and degradation and the embryonic cell cycle ANDREW W. MURRAY Department of
More information16 The Cell Cycle. Chapter Outline The Eukaryotic Cell Cycle Regulators of Cell Cycle Progression The Events of M Phase Meiosis and Fertilization
The Cell Cycle 16 The Cell Cycle Chapter Outline The Eukaryotic Cell Cycle Regulators of Cell Cycle Progression The Events of M Phase Meiosis and Fertilization Introduction Self-reproduction is perhaps
More informationCOMMENTARY. Mitotic control by metaphase-promoting factor and cdc proteins MANFRED J. LOHKA. Introduction
COMMENTARY Mitotic control by metaphase-promoting factor and cdc proteins MANFRED J. LOHKA Department of Cellular and Structural Biology, University of Colorado School of Medicine, B-111, 4200 East Ninth
More informationThe cell cycle entails an ordered series of macromolecular
21 REGULATING THE EUKARYOTIC CELL CYCLE This cultured rat kidney cell in metaphase shows condensed chromosomes (blue), microtubules of the spindle apparatus (red), and the inner nuclear envelope protein
More informationCyclin Dependent Kinases and Cell Cycle Control
Bioscience Reports, Vol. 22, Nos. 5 and 6, October and December 2002 ( 2002) NOBEL LECTURE 9 DECEMBER, 2001 Cyclin Dependent Kinases and Cell Cycle Control Paul M. Nurse The discovery of major regulators
More informationAnalysis of the Cdc28 protein kinase complex by dosage suppression
J. Cell Set. Suppl. 12, 2 9-37 (1989) Printed in Great Britain The Company of Biologists Lim ited 1989 29 Analysis of the Cdc28 protein kinase complex by dosage suppression STEVEN I. REED*, JEFFREY A.
More information7.06 Problem Set #4, Spring 2005
7.06 Problem Set #4, Spring 2005 1. You re doing a mutant hunt in S. cerevisiae (budding yeast), looking for temperaturesensitive mutants that are defective in the cell cycle. You discover a mutant strain
More informationPlant Molecular and Cellular Biology Lecture 8: Mechanisms of Cell Cycle Control and DNA Synthesis Gary Peter
Plant Molecular and Cellular Biology Lecture 8: Mechanisms of Cell Cycle Control and DNA Synthesis Gary Peter 9/10/2008 1 Learning Objectives Explain why a cell cycle was selected for during evolution
More informationCell Cycle Control in the Fission Yeast Schizosaccharomyces pombe
Journal of Generul Microbiology ( 1989, 131, 2 123-2 127. Printed in Great Britain 2123 Cell Cycle Control in the Fission Yeast Schizosaccharomyces pombe The Tenth Fleming Lecture ByPAUL NURSE Imperial
More informationThree different fusions led to three basic ideas: 1) If one fuses a cell in mitosis with a cell in any other stage of the cell cycle, the chromosomes
Section Notes The cell division cycle presents an interesting system to study because growth and division must be carefully coordinated. For many cells it is important that it reaches the correct size
More informationLife Sciences 1a: Section 3B. The cell division cycle Objectives Understand the challenges to producing genetically identical daughter cells
Life Sciences 1a: Section 3B. The cell division cycle Objectives Understand the challenges to producing genetically identical daughter cells Understand how a simple biochemical oscillator can drive the
More informationLecture 10: Cyclins, cyclin kinases and cell division
Chem*3560 Lecture 10: Cyclins, cyclin kinases and cell division The eukaryotic cell cycle Actively growing mammalian cells divide roughly every 24 hours, and follow a precise sequence of events know as
More informationAnalysis and Simulation of Biological Systems
Analysis and Simulation of Biological Systems Dr. Carlo Cosentino School of Computer and Biomedical Engineering Department of Experimental and Clinical Medicine Università degli Studi Magna Graecia Catanzaro,
More informationThe Cell Cycle/Le Cycle cellulaire SMC6052/BIM6028 IRCM
The Cell Cycle/Le Cycle cellulaire SMC6052/BIM6028 IRCM 1 février 2018 Benjamin H. Kwok, Ph.D. Chercheur principal, Institut de recherche en immunologie et en cancérologie Professeur sous octroi agrégé,
More informationA simple model for the eukaryotic cell cycle. Andrea Ciliberto
A simple model for the eukaryotic cell cycle Andrea Ciliberto The cell division cycle G1 cell division Start S (DNA Replication) Finish M (mitosis) G2/M G2 Kohn, Mol. Biol. Cell., 1999 How did we get to
More informationGetting In and Out of Mitosis*
Open Access NOBEL LAUREATE PERSPECTIVE Rambam Maimonides Medical Journal Getting In and Out of Mitosis* Tim Hunt, Ph.D., F.R.S. Nobel Laureate in Physiology or Medicine, 2001; Cancer Research UK, London
More informationConserved structural motifs in cyclins identified by sequence analysis
Conserved structural motifs in cyclins identified by sequence analysis JONATHAN H. A. NUGENT, CAROLINE E. ALFA, TANIA YOUNG and JEREMY S. HYAMS Department of iology, University College London, Gower Street,
More informationLecture #13 10/3 Dr. Wormington
Lecture #13 10/3 Dr. Wormington The Molecular "Logic" of the Cell Cycle Recap 1. Cdks generally present throughout cell cycle but are inactive w/o cyclin subunits. 2. Cyclin subunits synthesized in discrete
More informationBiology: Life on Earth
Biology: Life on Earth Eighth Edition Lecture for Chapter 11 The Continuity of Life: Cellular Reproduction Cellular Reproduction Intracellular activity between one cell division to the next is the cell
More informationBiophysical Chemistry 72 (1998)
Biophysical Chemistry 72 (1998) 153 167 Link between fertilization-induced Ca 2+ oscillations and relief from metaphase II arrest in mammalian eggs: a model based on calmodulin-dependent kinase II activation
More informationCELL CYCLE AND DIFFERENTIATION
CELL CYCLE AND DIFFERENTIATION Dewajani Purnomosari Department of Histology and Cell Biology Faculty of Medicine Universitas Gadjah Mada d.purnomosari@ugm.ac.id WHAT IS CELL CYCLE? 09/12/14 d.purnomosari@ugm.ac.id
More informationAP Biology Unit 6 Practice Test 1. A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8
AP Biology Unit 6 Practice Test Name: 1. A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms
More informationName Chapter 10: Chromosomes, Mitosis, and Meiosis Mrs. Laux Take home test #7 DUE: MONDAY, NOVEMBER 16, 2009 MULTIPLE CHOICE QUESTIONS
MULTIPLE CHOICE QUESTIONS 1. A bacterial chromosome consists of: A. a linear DNA molecule many times larger than the cell. B. a circular DNA molecule many times larger than the cell. C. a circular DNA
More informationEssential Knowledge: In eukaryotes, heritable information is passed to the next generation via processes that include the cell cycle and mitosis OR
Essential Knowledge: In eukaryotes, heritable information is passed to the next generation via processes that include the cell cycle and mitosis OR meiosis plus fertilization Objective: You will be able
More informationHonors Biology Test Chapter 8 Mitosis and Meiosis
Honors Biology Test Chapter 8 Mitosis and Meiosis 1. In mitosis, if a parent cell has 16 chromosomes, each daughter cell will have how many chromosomes? a. 64 b. 32 c. 16 d. 8 e. 4 2. Chromatids that are
More informationOverview of the cell cycle
Chapter 2 Overview of the cell cycle 2.1 The organisation of cell cycle in eukaryotes During the cell cycle, the typical eukaryotic cell goes through a series of well defined phases, to divide into two
More information2. Which of the following are NOT prokaryotes? A) eubacteria B) archaea C) viruses D) ancient bacteria
1. Which of the following statements is FALSE? A) Errors in chromosome separation are rarely a problem for an organism. B) Errors in chromosome separation can result in a miscarriage. C) Errors in chromosome
More informationMitotic role for the Cdc28 protein kinase of Saccharomyces cerevisiae
Proc. Nati. cad. Sci. US Vol. 87, pp. 5697-5701, ugust 1990 Genetics Mitotic role for the Cdc28 protein kinase of Saccharomyces cerevisiae STEVEN I. REED ND CURT WITTENBERG Department of Molecular Biology,
More informationA diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). As in humans, sex chromosomes determine sex: XX in females and XY in males.
Multiple Choice Use the following information for questions 1-3. A diploid somatic cell from a rat has a total of 42 chromosomes (2n = 42). As in humans, sex chromosomes determine sex: XX in females and
More informationCHAPTER 12 - THE CELL CYCLE (pgs )
CHAPTER 12 - THE CELL CYCLE (pgs. 228-245) CHAPTER SEVEN TARGETS I. Describe the importance of mitosis in single-celled and multi-cellular organisms. II. Explain the organization of DNA molecules and their
More informationLearning Objectives LO 3.7 The student can make predictions about natural phenomena occurring during the cell cycle. [See SP 6.4]
Big Ideas 3.A.2: In eukaryotes, heritable information is passed to the next generation via processes that include the cell cycle and mitosis or meiosis plus fertilization. CHAPTER 13 MEIOSIS AND SEXUAL
More informationI993. Signalling from the Plasma Membrane to the Nucleus 92 I
Cyclins and their associated cyclin-dependent kinases in the human cell cycle Jonathon Pines WellcomdCRC Institute, Tennis Court Road, Cambridge CB2 IQR, U.K. Progress through the cell cycle is determined
More informationSwitches and Latches in the Control of Cell Division
Switches and Latches in the Control of Cell Division Tim Hunt, Cancer Research UK Emerging Patterns, Singapore, 3 March 2015 All Living Things are Made of Cells (Which are very, very small) Cells only
More information3.a.2- Cell Cycle and Meiosis
Big Idea 3: Living systems store, retrieve, transmit and respond to information essential to life processes. 3.a.2- Cell Cycle and Meiosis EU 3.A: Heritable information provides for continuity of life.
More informationnutrients growth & division repellants movement
Network Dynamics and Cell Physiology John J. Tyson Department of Biological Sciences & Virginia Bioinformatics Institute Outline 1. Cell Signaling: Physiology 2. Cell Signaling: Molecular Biology 3. Chemical
More information12/5/2014. The cell cycle and cell death. The cell cycle: cells duplicate their contents and divide
The cell cycle and cell death The cell cycle: cells duplicate their contents and divide 1 The cell cycle may be divided into 4 phases Eucaryotic cell division: Mitosis (nuclear division) Cytokinesis (cell
More informationBiology, 7e (Campbell) Chapter 13: Meiosis and Sexual Life Cycles
Biology, 7e (Campbell) Chapter 13: Meiosis and Sexual Life Cycles Chapter Questions 1) What is a genome? A) the complete complement of an organism's genes B) a specific sequence of polypeptides within
More informationReading Assignments. A. Systems of Cell Division. Lecture Series 5 Cell Cycle & Cell Division
Lecture Series 5 Cell Cycle & Cell Division Reading Assignments Read Chapter 18 Cell Cycle & Cell Death Read Chapter 19 Cell Division Read Chapter 20 pages 659-672 672 only (Benefits of Sex & Meiosis sections)
More informationLecture Series 5 Cell Cycle & Cell Division
Lecture Series 5 Cell Cycle & Cell Division Reading Assignments Read Chapter 18 Cell Cycle & Cell Death Read Chapter 19 Cell Division Read Chapter 20 pages 659-672 672 only (Benefits of Sex & Meiosis sections)
More informationModeling the cell division cycle: cdc2 and cyclin interactions
Proc. Nati. Acad. Sci. USA Vol. 88, pp. 7328-7332, August 1991 Cell Biology Modeling the cell division cycle: cdc2 and cyclin interactions (maturation promoting factor/metaphase arrest/weel/cdc25) JOHN
More informationCELL CYCLE AND GROWTH REGULATION
CELL CYCLE AND GROWTH REGULATION The cell cycle is the set of stages through which a cell progresses from one division to the next. Interphase is the period between mitotic cell divisions; divided into
More informationRegulation of gene expression. Premedical - Biology
Regulation of gene expression Premedical - Biology Regulation of gene expression in prokaryotic cell Operon units system of negative feedback positive and negative regulation in eukaryotic cell - at any
More informationMeiosis and Sexual Life Cycles
Chapter 13 Meiosis and Sexual Life Cycles Lecture Outline Overview Living organisms are distinguished by their ability to reproduce their own kind. Offspring resemble their parents more than they do less
More informationTransport between cytosol and nucleus
of 60 3 Gated trans Lectures 9-15 MBLG 2071 The n GATED TRANSPORT transport between cytoplasm and nucleus (bidirectional) controlled by the nuclear pore complex active transport for macro molecules e.g.
More informationCHAPTER 15 LECTURE SLIDES
CHAPTER 15 LECTURE SLIDES Prepared by Brenda Leady University of Toledo To run the animations you must be in Slideshow View. Use the buttons on the animation to play, pause, and turn audio/text on or off.
More informationLecture Series 5 Cell Cycle & Cell Division
Lecture Series 5 Cell Cycle & Cell Division Reading Assignments Read Chapter 18 Cell Cycle & Cell Division Read Chapter 19 pages 651-663 663 only (Benefits of Sex & Meiosis sections these are in Chapter
More informationTriggering the all-or-nothing switch into mitosis
512 Review Triggering the all-or-nothing switch into mitosis Patrick H. O Farrell The past decade of cell cycle investigations has identified many roads not taken. The kinase that drives mitosis can be
More informationDegeneracy. Two types of degeneracy:
Degeneracy The occurrence of more than one codon for an amino acid (AA). Most differ in only the 3 rd (3 ) base, with the 1 st and 2 nd being most important for distinguishing the AA. Two types of degeneracy:
More informationStudent Learning Outcomes: Nucleus distinguishes Eukaryotes from Prokaryotes
9 The Nucleus Student Learning Outcomes: Nucleus distinguishes Eukaryotes from Prokaryotes Explain general structures of Nuclear Envelope, Nuclear Lamina, Nuclear Pore Complex Explain movement of proteins
More informationZool 3200: Cell Biology Exam 5 4/27/15
Name: Trask Zool 3200: Cell Biology Exam 5 4/27/15 Answer each of the following short answer questions in the space provided, giving explanations when asked to do so. Circle the correct answer or answers
More informationMEIOSIS DR. A. TARAB DEPT. OF BIOCHEMISTRY HKMU
MEIOSIS DR. A. TARAB DEPT. OF BIOCHEMISTRY HKMU Meiosis is a special type of cell division necessary for sexual reproduction in eukaryotes such as animals, plants and fungi The number of sets of chromosomes
More informationMathematical model of the fission yeast cell cycle with checkpoint controls at the G1/S, G2/M and metaphase/anaphase transitions
Biophysical Chemistry 72 (1998) 185 200 Mathematical model of the fission yeast cell cycle with checkpoint controls at the G1/S, G2/M and metaphase/anaphase transitions Bela Novak a, *, Attila Csikasz-Nagy
More informationIntroduction. Gene expression is the combined process of :
1 To know and explain: Regulation of Bacterial Gene Expression Constitutive ( house keeping) vs. Controllable genes OPERON structure and its role in gene regulation Regulation of Eukaryotic Gene Expression
More informationTopic 8 Mitosis & Meiosis Ch.12 & 13. The Eukaryotic Genome. The Eukaryotic Genome. The Eukaryotic Genome
Topic 8 Mitosis & Meiosis Ch.12 & 13 The Eukaryotic Genome pp. 244-245,268-269 Genome All of the genes in a cell. Eukaryotic cells contain their DNA in long linear pieces. In prokaryotic cells, there is
More informationQuiz answers. Allele. BIO 5099: Molecular Biology for Computer Scientists (et al) Lecture 17: The Quiz (and back to Eukaryotic DNA)
BIO 5099: Molecular Biology for Computer Scientists (et al) Lecture 17: The Quiz (and back to Eukaryotic DNA) http://compbio.uchsc.edu/hunter/bio5099 Larry.Hunter@uchsc.edu Quiz answers Kinase: An enzyme
More informationV5 Cell Cycle. In cells with a nucleus (eukaryotes), the cell cycle can be divided in 2 brief periods:
V5 Cell Cycle The cell cycle, or cell-division cycle, is the series of events that takes place in a cell leading to its division and duplication (replication). In cells without a nucleus (prokaryotes),
More informationBiology Kevin Dees. Chapter 13 Meiosis and Sexual Life Cycles
Chapter 13 Meiosis and Sexual Life Cycles Reproduction Characteristic of all living things Reproduction also involves the transmission of traits from one generation to the next; inheritance Heredity Latin
More informationChapter 13 Meiosis and Sexual Life Cycles. Reproduction
Chapter 13 Meiosis and Sexual Life Cycles Reproduction Characteristic of all living things Reproduction also involves the transmission of traits from one generation to the next; inheritance Heredity Latin
More informationACCELERATE ITS BIOCHEMICAL PROCESSES WHICH WERE SLOWED DOWN BY MITOSIS. THE LENGTH OF THE G1 PHASE CREATES THE DIFFERENCE BETWEEN FAST DIVIDING
CHAPTER 1: OVERVIEW OF THE CELL CYCLE THE THREE STAGES OF INTERPHASE: INTERPHASE BEFORE A CELL CAN ENTER CELL DIVISION, IT NEEDS TO PREPARE ITSELF BY REPLICATING ITS GENETIC INFORMATION AND ALL OF THE
More informationSexual Reproduction and Meiosis. Outline. Random?? fertilization. Chapter 13
Sexual Reproduction and Meiosis Chapter 13 Outline Reduction Division Unique Features of Meiosis Prophase I Metaphase I Completing Meiosis Second Meiotic Division Sexual Reproduction Origin and Maintenance
More information10 CELL DIVISION AND MITOSIS
10 CELL DIVISION AND MITOSIS Chapter Outline Why It Matters 10.1 THE CYCLE OF CELL GROWTH AND DIVISION: OVERVIEW The products of mitosis are genetic duplicates of the dividing cell Chromosomes are the
More informationInvestigation 7 Part 1: CELL DIVISION: MITOSIS
Investigation 7 Part 1: CELL DIVISION: MITOSIS How do eukaryotic cells divide to produce genetically identical cells? BACKGROUND One of the characteristics of living things is the ability to replicate
More informationReminders about Eukaryotes
BIO 5099: Molecular Biology for Computer Scientists (et al) Lecture 16: Eukaryotes at last! http://compbio.uchsc.edu/hunter/bio5099 Larry.Hunter@uchsc.edu Reminders about Eukaryotes Eukaryotes arose around
More informationCellular Division. copyright cmassengale
Cellular Division 1 Cell Division All cells are derived from pre- existing cells New cells are produced for growth and to replace damaged or old cells Differs in prokaryotes (bacteria) and eukaryotes (protists,
More informationReview (V1): Phases of Cell Cycle
Review (V1): Phases of Cell Cycle The cell cycle consists of 4 distinct phases: - G 1 phase, - S phase (synthesis), - G 2 phase - and M phase (mitosis). Interphase: combines G 1, S, and G 2 Activation
More information1- Below is a list of cell cycle phases matched with specific processes. Choose the correct pairing:
Name: NetID: Exam 4 - Version 2 November 13, 2018 Dr. A. Pimentel Instructions: 1- Select the BEST answer for each question 2- Use pencil to mark your responses in the answer sheet. 3- You can mark your
More informationLesson Overview Meiosis
11.4 THINK ABOUT IT As geneticists in the early 1900s applied Mendel s laws, they wondered where genes might be located. They expected genes to be carried on structures inside the cell, but which structures?
More informationBiology Unit 6 Chromosomes and Mitosis
Biology Unit 6 Chromosomes and Mitosis 6:1 Chromosomes DNA GENES CHROMATIN/CHROMOSOMES CHROMOSOMES/CHROMATIN are made of units called GENES. GENES are made of a compound called deoxyribonucleic acid or
More information1. Draw, label and describe the structure of DNA and RNA including bonding mechanisms.
Practicing Biology BIG IDEA 3.A 1. Draw, label and describe the structure of DNA and RNA including bonding mechanisms. 2. Using at least 2 well-known experiments, describe which features of DNA and RNA
More informationLesson Overview Meiosis
11.4 Chromosomes strands of DNA and protein contain the genes. genes are located in specific positions on chromosomes. Humans receive a set (23) of chromosomes from each parent. 23 chromosomes from mom
More informationDr. Fred Cross, Rockefeller (KITP Bio Networks 3/26/2003) 1
Outline Cell growth as the driver for cell cycle (in microbes): coordination of growth and division A basic principle organizing cell cycle control: why cyclin-dependent kinase activity must oscillate
More informationBiology I Fall Semester Exam Review 2014
Biology I Fall Semester Exam Review 2014 Biomolecules and Enzymes (Chapter 2) 8 questions Macromolecules, Biomolecules, Organic Compunds Elements *From the Periodic Table of Elements Subunits Monomers,
More informationNumber of questions TEK (Learning Target) Biomolecules & Enzymes
Unit Biomolecules & Enzymes Number of questions TEK (Learning Target) on Exam 8 questions 9A I can compare and contrast the structure and function of biomolecules. 9C I know the role of enzymes and how
More informationCh. 13 Meiosis & Sexual Life Cycles
Introduction Ch. 13 Meiosis & Sexual Life Cycles 2004-05 Living organisms are distinguished by their ability to reproduce their own kind. -Offspring resemble their parents more than they do less closely
More information5.1. Cells have distinct phases of growth, reproduction, and normal functions. G 1. Cell Growth and Division CHAPTER 5 THE CELL CYCLE KEY CONCEPT
SECTION 5.1 THE CELL CYCLE Study Guide KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. VOCABULARY cell cycle mitosis cytokinesis The cell cycle has four main stages.
More informationNumerical analysis of a comprehensive model of M-phase control in Xenopus oocyte extracts and intact embryos
Journal of Cell Science 106, 1153-1168 (1993) Printed in Great Britain The Company of Biologists Limited 1993 1153 Numerical analysis of a comprehensive model of M-phase control in Xenopus oocyte extracts
More informationUnit 6 Test: The Cell Cycle
Name Date Class Mrs. Knight Biology EHS Unit 6 Test: The Cell Cycle 1. What are the four main stages of the cell cycle (correct order)? A. G 1, S, G 0, M C. G 2, S, G 1, M B. G 1, S, G 2, M D. M, G 2,
More information1. If a eukaryotic cell has a single set of chromosomes, it is called A. haploid B. diploid C. polypoid
Reproduction 1. If a eukaryotic cell has a single set of chromosomes, it is called A. haploid B. diploid C. polypoid 2. Which of the following cell functions are maintained by cell division? A. growth,
More information2:1 Chromosomes DNA Genes Chromatin Chromosomes CHROMATIN: nuclear material in non-dividing cell, composed of DNA/protein in thin uncoiled strands
Human Heredity Chapter 2 Chromosomes, Mitosis, and Meiosis 2:1 Chromosomes DNA Genes Chromatin Chromosomes CHROMATIN: nuclear material in non-dividing cell, composed of DNA/protein in thin uncoiled strands
More informationUnit 2: Cellular Chemistry, Structure, and Physiology Module 5: Cellular Reproduction
Unit 2: Cellular Chemistry, Structure, and Physiology Module 5: Cellular Reproduction NC Essential Standard: 1.2.2 Analyze how cells grow and reproduce in terms of interphase, mitosis, and cytokinesis
More informationCH 13 Meiosis & Sexual Life Cycles
CH 13 Meiosis & Sexual Life Cycles AP Biology 2005-2006 Cell division / Asexual reproduction Mitosis produce cells with same information identical daughter cells exact copies clones same amount of DNA
More informationChapter 11: The Continuity of Life: Cellular Reproduction. What is Cellular Reproduction?
Chapter 11: The Continuity of Life: Cellular Reproduction What is Cellular Reproduction? Answer: The division of a parent cell into two daughter cells Requirements of Each Daughter Cell: 1) Necessary genomic
More informationChapter 12: The Cell Cycle
Name Period Chapter 12: The Cell Cycle Overview: 1. What are the three key roles of cell division? State each role, and give an example. Key Role Example 2. What is meant by the cell cycle? Concept 12.1
More informationHuman biology Laboratory. Cell division. Lecturer Maysam A Mezher
Human biology Laboratory Cell division Lecturer Maysam A Mezher CHROMOSOME STRUCTURE 1. During nuclear division, the DNA (as chromatin) in a Eukaryotic cell's nucleus is coiled into very tight compact
More informationCell division / Asexual reproduction
Cell division / Asexual reproduction Mitosis produces cells with same information identical daughter cells exact copies clones same amount of DNA same number of chromosomes same genetic information Asexual
More informationCell Division (Outline)
Cell Division (Outline) 1. Overview of purpose and roles. Comparison of prokaryotic and eukaryotic chromosomes and relation between organelles and cell division. 2. Eukaryotic cell reproduction: asexual
More informationSexual Reproduction and Meiosis. Chapter 11
Sexual Reproduction and Meiosis Chapter 11 1 Sexual life cycle Made up of meiosis and fertilization Diploid cells Somatic cells of adults have 2 sets of chromosomes Haploid cells Gametes (egg and sperm)
More informationNewly made RNA is called primary transcript and is modified in three ways before leaving the nucleus:
m Eukaryotic mrna processing Newly made RNA is called primary transcript and is modified in three ways before leaving the nucleus: Cap structure a modified guanine base is added to the 5 end. Poly-A tail
More informationDevelopmental Role and Regulation of cortex, a Meiosis-Specific Anaphase-Promoting Complex/Cyclosome Activator
Developmental Role and Regulation of cortex, a Meiosis-Specific Anaphase-Promoting Complex/Cyclosome Activator Jillian A. Pesin 1,2, Terry L. Orr-Weaver 1,2* 1 Department of Biology, Massachusetts Institute
More informationMeiosis and Sexual Reproduction. Chapter 9
Meiosis and Sexual Reproduction Chapter 9 9.1 Genes and Alleles Genes Sequences of DNA that encode heritable traits Alleles Slightly different forms of the same gene Each specifies a different version
More informationMitosis & Meiosis. PPT Questions. 4. Why must each new cell get a complete copy of the original cell s DNA?
1. From where do new cells arise? Mitosis & Meiosis PPT Questions 2. Why does the body constantly make new cells? 3. Is cell division the same in all cells? Explain. 4. Why must each new cell get a complete
More informationAnswer Key. Cell Growth and Division
Cell Growth and Division Answer Key SECTION 1. THE CELL CYCLE Cell Cycle: (1) Gap1 (G 1): cells grow, carry out normal functions, and copy their organelles. (2) Synthesis (S): cells replicate DNA. (3)
More informationThe Microscopic Observation of Mitosis in Plant and Animal Cells
The Microscopic Observation of Mitosis in Plant and Animal Cells Prelab Assignment Before coming to lab, read carefully the introduction and the procedures for each part of the experiment, and then answer
More informationMeiosis and Life Cycles - 1
Meiosis and Life Cycles - 1 We have just finished looking at the process of mitosis, a process that produces cells genetically identical to the original cell. Mitosis ensures that each cell of an organism
More informationChapter 11: The Continuity of Life: Cellular Reproduction
Chapter 11: The Continuity of Life: Cellular Reproduction Chapter 11: Cellular Reproduction What is Cellular Reproduction? Answer: The division of a parent cell into two daughter cells Requirements of
More informationANALYSIS OF BIOLOGICAL NETWORKS USING HYBRID SYSTEMS THEORY. Nael H. El-Farra, Adiwinata Gani & Panagiotis D. Christofides
ANALYSIS OF BIOLOGICAL NETWORKS USING HYBRID SYSTEMS THEORY Nael H El-Farra, Adiwinata Gani & Panagiotis D Christofides Department of Chemical Engineering University of California, Los Angeles 2003 AIChE
More informationStudy Guide A. Answer Key. Cell Growth and Division. SECTION 1. THE CELL CYCLE 1. a; d; b; c 2. gaps 3. c and d 4. c 5. b and d 6.
Cell Growth and Division Answer Key SECTION 1. THE CELL CYCLE 1. a; d; b; c 2. gaps 3. c and d 4. c 5. b and d 6. G 1 7. G 0 8. c 9. faster; too large 10. volume 11. a and b 12. repeating pattern or repetition
More informationName 8 Cell Cycle and Meiosis Test Date Study Guide You must know: The structure of the replicated chromosome. The stages of mitosis.
Name 8 Cell Cycle and Meiosis Test Date Study Guide You must know: The structure of the replicated chromosome. The stages of mitosis. The role of kinases and cyclin in the regulation of the cell cycle.
More informationProf. Fahd M. Nasr. Lebanese university Faculty of sciences I Department of Natural Sciences.
Prof. Fahd M. Nasr Lebanese university Faculty of sciences I Department of Natural Sciences fnasr@ul.edu.lb B3206 Microbial Genetics Eukaryotic M. G. The yeast Saccharomyces cerevisiae as a genetic model
More informationCell Division THE MAJOR STEPS OF CELL DIVISION: 10/28/2013. When does DNA replicate? The first step of cell division is DNA replication:
Cell Division Biology 105 Laboratory 8 THE MAJOR STEPS OF CELL DIVISION: When does DNA replicate? The first step of cell division is DNA replication: This occurs just prior to cell division. Cells need
More information